Sorry no. I agree with your friend. If you can afford a new one I would buy new. You can only surface clean the second hand one, another persons sweat etc will have penetrated deeper than where you can clean.

How old is ds? Is it a full size mattress or for a cot or something? If it's going to be used for a long time I would maybe invest in a decent new one but if you trust the seller and you're getting a good deal it could be fine. I sold what had been an expensive cot mattress on ebay that was in excellent condition and hadn't been used for long - to someone who was buying it for their dog! I was devastated when they came to collect it and told me that!

If it is in good nick and clean, I don't see why not. I always use a waterproof mattress cover on top of mattresses. Alternatively I just bought a single foam mattress from Amazon basics and it's very comfy and reasonnably priced.

It's for my 11 year old. It's a really good quality memory foam one. Owner's house looks very clean. He said their son used it occasionally but that's all I know. Seller is a Dr - which is vaguely comforting. Part of the problem is the new ones smell so bad!

A mattress is one thing I would never buy second hand. I sold mine after having it for a year because I just didn't get on with it and I hoovered it first. I got nearly half a cylinder of dust and presumably dead skin cells out of it. And I use a mattress protector and two sheets at all times. So despite having a protector, flat sheet and then a fitted sheet on top at all times, changed weekly, it still managed to accumulate all that! I was horrified.

Memory foam does offgas a little but it really isn't that bad. The firmer the foam, the less it smells. My new one is full foam and a 4 in firmness rating and I noticed a slight smell for about 2 days. Not enough that it bothered me, couldn't even smell it unless I pressed my face against it and it dissipates quickly. Walk on it when it first arrives and then leave it exposed for 12 hours and the worst of it is gone.

I wanted a really nice one but had no money so I got what I wanted on a monthly finance plan, paying £30 a month for a year. I barely even notice I'm paying it. It's what? One less visit to Nandos a month? Might be an option if you have a decent credit score.

I would buy it, we got a single mattress that is sitting at just under £600 pounds for £50 off gumtree, couple had bought it for when elderly parents came to stay but then had to put them in a home. The mattress is fantastic quality and we could not have afforded to buy it new. If you are worried buy a cover like suggested above and if you want you can even buy a new mattress topper. I bet your son won't be in the least bit worried!